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I am just in the process of giving Deniz Festers a hard time about the air kommands with the holes drilled in the masts, so that the mast would snap right at the weakest point.... but several machines were cracking just in normal use and evidently ASRA and he clashed over it.... if any of the ASRA people involved can let me know the facts, I would appreciate it.... I want to get the facts straight before launching into him
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Drilling a mast in mid section?? How f..g stupid!!Let me regale my experiences with drilled masts.It may not have been an Aer Kommant but I lifted a VW powered gyro off 1 unfortunate named Jeff at Whittingham after he turtled it nose first, snapping at the mast just above shoulder height, right where it had been drilled through.The machine landed on him, the top of the chair rail got him, fortunately he had a crash hat on, unfortunately with about 150kg of maehine impacting on him, the helmet wasn"t good enough.Jeff ended up with a fractured skull, broken jaw and would have died except for our intervention as he nearly choked on his shattered dentures. He spent 6 weeks in Hospital from what I recall. Never mind the chemical burns he got from the petrol.As an engineer I can say it would have to be the most foolish thing to do, to introduce a fault into the middle of one of the most stressed members in the whole airframe.Let me warn about "extreme fibre stress" where as Sam La Bruna discovered, fatally, that any hole in the extreme fibre at a concentrated point of stress will result in failure. Hub Bars and masts are the last thing you want a hole in at the point in the member where there is a maximum bending moment.Another thing to consider is that any machining operation which cuts into the metal will disturb that metal out to the metal crystal boundaries and beyond, so if a 6mmø hole is drilled, the damage carries out about another mm, so the hole effectively is 8mmø.Jeff"s mast was drilled at 90° to the direction of travel, but it would be phenominally stupid to think that the mast is not being flexed sideways as well as back & forth.Please - if you have a mast drilled like this, replace it immediately.
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Thanks Nick, yes, I am just chasing the facts on the AC mast holes.... evidently there were holes drilled about the top of the seat level so that in a rotor strike, the mast would snap off and the machine would stay on its wheels.... ASRA evidently found that there was cracks propagating from the holes without there being any blade strikes
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Oh, now I get it, so the mast snaps off right at a height that the sharp end can decapitate you? Sever your spinal cord? Smash you in the back of the head with 8,000,000 Joules of energy or around 11,000 instantaneous horsepower?Where"s the guarantee it will behave nicely and not hit the pilot? At least if the mast does not snap, the rotors are held away by the mast, and it protects you in a roll over.I think this "reason" is totally flawed and foolishly put forth. Based on the accidents I"ve seen, the guys with no midsection holes walk away, the others get ambulanced away to never fly again.
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Probably like the crash position on airplanes..... it is cheaper to pay out widows, than keep paying medical bills for survivors.... maybe his death trap machines were actually designed to decapitate people after all? Anyway, ASRA evidently stuck to their guns and the masts with the holes had to go.... I just want to find the actual facts
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